I found one of jimineecrickets old post about his .25 s510 and it is eerily similar to what mine is doing. I have the same rifle (s510 .25) I get a nice shot string over the chrony but the accuracy just isn't there. I shot 4 groups today and they all were stringing vertically at 25 yards. I'm guessing my problem is something to do with the stock or barrel band. Does anybody know what the issue was with Jim's rifle and how he fixed it? I know it was a long time ago but I figured I'd ask because my gun is behaving the EXACT same way. Here is his thread:
http://www.network54.com/Forum/79537/th ... ing+issues!
shooting a few hard pellets like the Kodiak into some old blankets or t-shirts so you can retrieve the pellets and have a closer look to see if it is clipping if that's what you suspect. I like to work smart, not hard, and gather all the evidence I can to help me make an educated "guess" before I start taking something apart that may not need to be.
You could try a different scope or mounts just to cover your bases. Go for the basics first (o-rings etc..) and go from there.
Good luck and keep us posted.